Ewart— Variation : Germinal and Environmental. 368 
Even now, it is only necessary to interbreed half-bred animals, the offspring 
of two varieties that have long lived apart, or cross-fertilize plants in which self- 
fertilization has been the rule, in order to obtain an epidemic of variation, to 
induce a more or less prolonged period of ‘“ sporting.”’* 
From the offspring of the half-breeds varying so much, it is evident that, 
though they were all wonderfully like wild rabbits, the stability uf the wild rabbit 
had been lost, that, as it is said of plants, crossing had broken down the “ consti- 
tution.” But it may be mentioned, the stability can soon be restored by engaging 
in inter-breeding—which usually leads to exactly opposite results from inter- 
crossing—and that even without close inter-breeding the “ sporting” tendency 
oradually wanes. 
Two of the offspring of the half-breeds (the grey- and the squirrel-coloured 
ones) I crossed with pure white does, and with grey quarter-wild does. The 
invariable result was a litter of mixed colours. 
By the crossings mentioned, and many others on record, I satisfied myself (1) 
that under ordinary circumstances wild rabbits, bred with tame white bucks or 
does, yielded grey rabbits ; (2) that half-wild rabbits, whether bred with each 
other or with white rabbits, yielded offspring of three or more colours; (3) that the 
offspring of two half-wild rabbits (even if grey), when bred with each other, or with 
the grey offspring of a half-wild and a white rabbit, yielded young of several 
colours; and (4) that there is an intimate relation between the colour and (a) the 
‘‘ wildness,” (6) the time maturity is reached, and (c) the rate of growth—white 
individuals being tamer and sooner mature than grey. 
(0). Result of mating does before and after the normal time. 
It is commonly believed by some (e.g, many gamekeepers and sportsmen) that 
rabbits begin to breed when about six weeks old, while others assert that they only 
reach maturity when six months old. At what age wild rabbits reach maturity I 
have not determined, but I find tame and half-wild does living under favourable 
conditions frequently mature during the fourteenth week, and have their first litter 
during the eighteenth or nineteenth week, ¢.c., before they are five months old. 
Anticipating that four grey does (the offspring of a half-wild buck and a white doe) 
born on the 8th February, 1899, would soon reach maturity, I placed one with an 
Angora buck on the 10th June, ¢.e. when thirteen weeks old. Though the doe was 
* Were this power of ‘‘ sporting”? (varying) lost, a species would lose its power of adapting itself to 
changes in the environment, and thus run the risk of extinction. Every pronounced change in the surround- 
ings usually leads to a certain amount of mixing up (with its inevitable intercrossing) of forms which, in their 
germ-plasm, if not in their outward characters, somewhat differ from each other. 
3H 2 
